and water from the latter: but if the water be too high it will rush out at t instead of steam, and if it be lower than it ought to be, then steam will issue out of the pipe u instead of water.

STEEL, iron mixed with other ingredients, and purified by fire; from which process it is whiter and of "a finer grain than before. Iron, on being made into steel, becomes harder than any other metal. It is tempered, or hardened, by plunging it, when hot, into cold water. If heated, and not subsequently plunged into water, it remains soft. Steel was formerly understood to be composed of iron, mixed with any stone that melted with readiness. It is now defined to be iron combined with carbon.

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cording to the analysis of Vaugelin, however, it still appears, that it contains a proportion of stony particles. This chemist found the composition of one kind of steel to consist of carbon, silica, pliosphorus, iron, and in three others, these four substances were always present, and in relative quantities nearly similar. It is not, however, concluded that phosphorus and silica are essential to the nature of steel.

Plumbago, or black lead, is a native mixture of iron and carbon, as steel is an artificial one; but the proportions are widely different. See CARBON, DIAMOND.

STEELYARD, or Roman balance, in mechanics, balance by which the gravities of different bodies are found, with the assistance of a single weight.

STERE, a Greek word implying solidity; in the new metrical system of France, it is a cubic metre. STEREOGRAPHY, the drawing of solids, the art of drawing the figures of the solids upon a plane.